H-R diagram

  • What is a “Normal” Star?

    What is a “Normal” Star?

    If we were talking about people, I’d say there’s no such thing as a “normal” person. We’re all weird in our own way — that’s what makes us unique and ourselves. However, there’s such a thing as a functional human…

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  • Observations of Star Birth

    Observations of Star Birth

    Astronomers have a pretty solid idea of how stars are born. They begin within the dense, cold dust of an interstellar cloud such as this one. They heat up and get more luminous as they contract, and then drop in…

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  • The Story of a Newborn Star

    The Story of a Newborn Star

    What happens when a star is born? A couple of posts ago, I explained how a protostar forms out of a dense cloud core within the interstellar medium. But…wait. What exactly is a protostar again? A protostar forms when one…

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  • The Orion Nebula: A Stellar Nursery

    The Orion Nebula: A Stellar Nursery

    One of my favorite objects to show people at astronomy outreach events is the Orion Nebula. Not only does it reside within a fairly well-known constellation, but it’s a gorgeous sight to see with a good telescope. There’s no time like…

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  • Star Mass and Density

    Star Mass and Density

    What makes a star shine bright? Much earlier on — probably months ago now — I explained how something called the proton-proton chain generates massive amounts of energy within stars, and enables them to fuel whole solar systems. That’s the battery…

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  • The Average Star

    The Average Star

    What the heck is the average star like? We’ve talked about a lot of stars over the past few weeks. We’ve discovered the vast distances between the stars, looked more closely at what really makes a star bright, and covered all…

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  • Star Types Demystified

    Star Types Demystified

    By now, I’ve introduced you to a lot of different ways to classify stars. Months ago, I talked about the different spectral classes — O, B, A, F, G, K, and M. Even before that, I told you about apparent visual…

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  • How Far Are the Stars?

    How Far Are the Stars?

    Stars don’t look small because they’re really the size of pinholes in a blanket. The smallest are the size of Earth. The largest have 128,865,170 times Earth’s diameter. They look small in the sky because they’re distant. It’s for the same…

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  • Star Luminosity Classes

    Star Luminosity Classes

    What do you think it would mean for a star to be in a specific luminosity class? I mean…does that mean they go to school to learn how to be bright? (Ha, ha…yeah, I know, bad astronomy pun.) Well…not quite.…

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  • Just How Big Are Stars?

    Just How Big Are Stars?

    Tell me about the stars you see in this image. They look like billions of little pinpricks of light, right? It’s hard to imagine that each one of these is probably the size of the sun…or much larger. And the…

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